Hot worked, fully dense, wear resistant, vanadium-rich, powder metallurgy cold work tool steel article with high impact toughness, made from nitrogen atomized pre-alloyed powders

摘要

In the present invention, there is disclosed a hot worked, fully dense, wear resistant, vanadium-rich, powder metallurgy cold work tool steel article with high impact toughness made from nitrogen atomized pre-alloyed powders, consisting essentially of 0.60 to 0.95 percent by weight of carbon; 0.10 to 2.0 percent by weight of manganese; up to 0.10 percent by weight of phosphorus; up to 0.15 percent by weight of sulfur; at the most up to 2 percent by weight of silicon; 6.00 to 9.00 percent by weight of chromium; up to 3.0 percent by weight of molybdenum; up to 1.0 percent by weight of tungsten; 2.00 to 3.30 percent by weight of vanadium; up to 0.15 percent by weight of nitrogen; balance iron and incidental impurities; wherein the maximum carbon content does not exceed the amount given by the following formula: Cimax = 0.60 + 0.177 (weight percent V û 1.0). Said articles if hardened and tempered to a hardness of at least 58 HRC have a dispersion of substantially all MC-type carbides within the range of 4 to 8 percent by volume and the maximum size of the MC-type carbides does not exceed about six microns in their longest dimension, whereby said article exhibits, as described herein, a C-notch impact strength exceeding 6.9 Nm.